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Filters: Tags: Projecting Future States 1-Predict or Map the Impact of Changing Permafrost (X)

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In Canada's subarctic?the boreal ecosystem that spans most of mainland Canada?the temperature is climbing, and the snowpack is thinning. Previous research has shown that snow is disappearing even faster than sea ice.
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Ongoing and rapid environmental change within western and northern Canada is of major societal and scientific concern and has local- to global-scale implications. There is an urgent need to understand the changes and develop improved diagnostic and predictive modeling tools to manage uncertain futures.
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In glacier-fed systems climate change may have various effects over a range of time scales, including increasing river discharge, flood frequency and magnitude. This study uses a combination of empirical monitoring and modelling to project the impacts of climate change on the glacial-fed Middle Fork Toklat River, Denali National Park, Alaska. We use a regional calibration of the model HBV to account for a paucity of long term observed flow data, validating a local application using glacial mass balance data and summer flow records. Two Global Climate Models (HADCM3 and CGCM2) and two IPCC scenarios (A2 and B2) are used to ascertain potential changes in meteorological conditions, river discharge, flood frequency...
The impact to the permafrost during and after wildfire was studied using 11 boreal forest fire sites including two controlled burns. Heat transfer by conduction to the permafrost was not significant during fire. Immediately following fire, ground thermal conductivity may increase 10-fold and the surface albedo can decrease by 50% depending on the extent of burning of the surficial organic soil. The thickness of the remaining organic layer strongly affects permafrost degradation and aggradation. If the organic layer thickness was not reduced during the burn, then the active layer (the layer of soil above permafrost that annually freezes and thaws) did not change after the burn in spite of the surface albedo decrease....
Pronounced step-wise atmospheric warming during the 20th century reduced ice cover in mountains by 25-50 percent. Net changes in average annual and mean summer temperatures responsible for this remarkable deglacierization are less than 2 degrees C, a small fraction of the warming that occurred at the end of the Pleistocene. Yet the effects of these changes on mountain landscapes have been profound. Alpine permafrost, which expanded during the Little Ice Age. now appears to be thinning and disappearing in many areas. Loss of alpine permafrost and glacier downwasting appear to be partly responsible for accelerated mass wasting and catastrophic rock-slope failures in high mountains. New lakes appeared during the Little...
To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate approximately 600 years of vegetation succession with a transition from a terrestrial forest to a sedge-dominated wetland over 100 years ago, and to a Sphagnum-dominated peatland in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing...
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The boreal forests of North America are undergoing major changes because of the direct effects of global warming and increased CO sub(2) levels. Plant production in the boreal forest is nutrient limited, and we examined how long-term fertilization affected growth of white spruce Picea glauca in the face of these major changes. We conducted a large-scale experiment by fertilizing two 1 km super(2) stands of white spruce in the southwestern Yukon with commercial NPK fertilizer from 1987 to 1994. Tree growth was measured by the width of annual increments in 60 trees from each of 2 control and of 2 matched fertilized 1 km super(2) sites for the period from 1977 to 1997 in a before, during, and after experimental design....
A soil-ecological site survey of Denali National Park and Preserve (Denali) completed in 2004 by the Natural Resources Conservation Service is used to provide a map of Gelisols. soils with permafrost within 2 m of the surface, and their sensitivity to disturbance. Three sensitivity classes are assigned, based on similarities in the degree and rapidity of change to soil properties and plant communities following disturbance, as well as return interval to the pre-disturbance condition. The model aggregates ecological sites into groups with similar plant community structure and species richness, two elements useful in evaluating wildlife habitat. Dynamic soil properties, such as thickness of organic mat. depth to water...
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Old Crow Flats is a 5600 km2 glaciolacustrine plain that straddles the forest-tundra ecotone in northern Yukon. Continuous taiga corridors occur in the entrenched river valleys, where annual mean ground temperatures (Tg) at the depth of zero annual amplitude at two locations were ?3.1 and ?4.0ºC in 2013. On the Flats, the vegetation cover is patchy, and Tg varied between ?5.1 and ?2.6ºC. Annual mean near-surface permafrost temperatures (Tps) measured on the Flats between 2008 and 2011 in patches of taiga, tall shrubs and low shrubs were correlated with local snow depth. Snow depth was controlled by vegetation height if the snow supply was not limited, for example, where low shrubs and large lakes dominate the landscape....
The Fairbanks Permafrost Experimental Station was established in 1945 near Fairbanks, Alaska. In 1946 vegetation was removed from two plots (the Linell plots) to investigate the impacts of vegetation disturbance on permafrost degradation. We revisited the sites in 2007 to evaluate the permafrost table using probes and direct current electrical resistivity. The permafrost table has expanded downward to 9.8 m at a site where all surface vegetation and organic material was removed. The permafrost surface has remained at 4.7 m depth since 1972 at a second site where vegetation was removed but organic material was left intact. In 2005 a Circumpolar Active Layer Monitoring Network (CALM) site was established at an undisturbed...
The boreal forests of North America are undergoing major changes because of the direct effects of global warming and increased CO sub(2) levels. Plant production in the boreal forest is nutrient limited, and we examined how long-term fertilization affected growth of white spruce Picea glauca in the face of these major changes. We conducted a large-scale experiment by fertilizing two 1 km super(2) stands of white spruce in the southwestern Yukon with commercial NPK fertilizer from 1987 to 1994. Tree growth was measured by the width of annual increments in 60 trees from each of 2 control and of 2 matched fertilized 1 km super(2) sites for the period from 1977 to 1997 in a before, during, and after experimental design....


map background search result map search result map Observation, Diagnosis, and Prediction of Environmental Change in Northwestern Canada Vegetation-Permafrost Relations within the Forest-Tundra Ecotone near Old Crow, Northern Yukon, Canada More comprehensive characterization of landslides in permafrost The Significance of Shifts in Precipitation Patterns: Modelling the Impacts of Climate Change and Glacier Retreat on Extreme Flood Events in Denali National Park, Alaska Characteristics of discontinuous permafrost based on ground temperature measurements and electrical resistivity tomography, southern Yukon, Canada Soil CO (sub 2) production in upland tundra where permafrost is thawing Climate and nutrient influences on the growth of white spruce trees in the boreal forests of the Yukon Climate Change Trends for the State of the Park Report, Denali National Park, Alaska Soil CO (sub 2) production in upland tundra where permafrost is thawing Climate and nutrient influences on the growth of white spruce trees in the boreal forests of the Yukon Climate Change Trends for the State of the Park Report, Denali National Park, Alaska Characteristics of discontinuous permafrost based on ground temperature measurements and electrical resistivity tomography, southern Yukon, Canada The Significance of Shifts in Precipitation Patterns: Modelling the Impacts of Climate Change and Glacier Retreat on Extreme Flood Events in Denali National Park, Alaska Vegetation-Permafrost Relations within the Forest-Tundra Ecotone near Old Crow, Northern Yukon, Canada Observation, Diagnosis, and Prediction of Environmental Change in Northwestern Canada More comprehensive characterization of landslides in permafrost